Polysulfide polymer sealant and lubricant



POLYSULFIDE POLYMER SEALANT AND LUBRICANT Blyde A. Perkins, Oakland,Calif., assiguor to Rockwell Manufacturing Company, Pittsburgh, Pa., acorporation of Pennsylvania No Drawing. Application June 11, 1953 SerialNo. 361,080

5 Claims. (Cl. 252-23) This invention relates to a new composition ofmatter and its method of preparation and is more particularly concernedwith a lubricant and sealing composition which is chemically inert toaliphatic hydrocarbons, mineral and vegetable oils, natural andmanufactured gases, oils and hydrocarbon gases containing large amountsof hydrogen sulfide or mercaptans. This composition is also resistant toweak mineral acids of about percent concentration, with the exception ofoxidizing acids, and weak alkalies up to pH of 13. The lubricant isresistant to aqueous solutions and water as well as mixtures ofhydrocarbon liquids and gases and water. The compositions is a verysatisfactory plug valve lubricating and sealing medium.

The lubrication of bearing contact parts, such as valves and likeapparatus, when exposed to line fluids of strong solvent action, i. e.,liquid hydrocarbons, has always presented a diflicult problem. Thisproblem is heightened when the line fluid consists of several types ofchemicals, all possessing strong solvent action. Thus, mixtures ofliquid hydrocarbons and water exert a solvent action and presentproblems that would not exist were either of these types of materialencountered solely as the line fluid. The problem of lubricating bearingparts, such as valves, may be heightened further when the line fluid isunder high pressure, may vary over a wide temperature range, may have awide variation in pH (ranging from a solution corresponding to a 10percent mineral acid concentration to one consisting of a weak alkaliwith a pH of 13), and may contain large amounts of hydrogen sulfide ormercaptans. All of the standard plug valve lubricants are usuallyreadily disintegrated when used for oil field services where theyencounter line fluids which are mixtures of hydrocarbons, water, acids,mercaptans, etc, thus necessitating frequent relubrication.

The lubrication of plug valves used in the oil fields has thereforecreated a demand for a lubricant and sealing medium which isparticularly inert with respect to a wide range of solvents and linepressures, and one that will maintain a good lubricating and sealingfilm over a wide range of temperature. The invention provides alubricant which is substantially resistant with respect to aliphatichydrocarbons, manufactured and natural gases, oils, dilute acids, weakalkalies, mixtures of oils and hydrocarbons with water, and oils andgases containing large amounts of mercaptans and hydrogen sulfide, andwhich seals off the line fluid under wide variations in temperature andpressure.

The major object of the invention is to provide a novel composition ofmatter containing a major amount of synthetic liquid polysulfide polymerthickened by the addition of a metallic soap in the presence ofuniformly dispersed carbon black, and the process of making the same.

A further object of the invention is to provide a novel composition ofmatter which has especial utility as a plug valve lubricant for generaloil field services composed of a major amount of synthetic liquidpolysulfide polymer having an average molecular weight of 1000-4000thicknited States Patent 0 2,818,384 Patented Dec. 31, 1957 ened bysolution therewith of a metallic soap and containing a dispersal ofcarbon black particles, and the process of making the same.

A further object of the invention is to provide a novel process formaking the foregoing wherein the polymer, carbon black and soap areadded to each other in a special order and under special controlledtemperature conditions.

Further objects of the invention will appear as the description proceedsin connection with the appended claims.

This lubricant and sealing material is composed mainly of syntheticpolysulfide polymers of the kind which are made by reactingdichloroethylformal and trichlorpropane together with a water dispersionof sodium hydrosulfide and sodium sulfite to produce a liquid syntheticpolymer of average molecular weight of 1000-4000, and have the followingaverage structure:

where X is an integer of about 6 for polymers of molecular weight of1000 and X is an integer of about 23 for polymers of molecular weight of4000. Occasionally in the chain of reoccurring units there is a sidemercaptan group.

The synthetic polymers which I have used are those commercially known asThiokol liquid polymer type LP-Z which has an average molecular weightof 4000, and Thiokol liquid polymer type LP-3 which has an averagemolecular weight of 1000. These polymers have different viscosities andthey blend in the mixture to attain desired viscosity of the material.

It is known that these synthetic liquid polysulfide polymers areresistant to oils and aliphatic hydrocarbons. However, these liquidpolymers alone do not have the physical properties required to serve assatisfactory sealing mediums for lubricated plug type valves,particularly over a wide range of temperatures, and in the inventionthey are modified for suitable consistency. This has been accomplishedby incorporating therewith a metallic soap such as aluminum stearate anda carbon black such as medium channel air-floated carbon black, wherebya plastic material is obtained which is satisfactory as a plug valvelubricant and seal and is satisfactorily resistant to the line fluids ofthe general oil field services. It has an elfective operating range from0 F. to 300 F. This new lubricant and seal maintains its viscosity up toas high as 450 F., but it is not usually recommended for temperatures inexcess of 300 B, because when the polymers are subjected to sustainedtemperatures of above 300 F. there may occur thermal breakdowns whichresult in the separation and hardening of the carbon black and metallicsoap and which completely change and make the lubricant unsatisfactoryas a valve lubricant and sealing medium.

To obtain a lubricant with the desired characteristics which would benecessary for this type of service, the synthetic polymers had to bethickened with a thickening agent which would give it a widertemperature range. Various metallic soaps were tried for thickening thepolymers, but all of the metallic soaps used proved at first to beinsoluble in both types of the synthetic liquid polymer. An importantdiscovery and feature of the invention is that I have found that by theincorporation of carbon black in the mixture, preferably of the mediumchannel air-floated grade, I am able to incorporate and dissolvemetallic soaps into the synthetic polymer matrices and obtain athickening and gelling action over a wide range of temperature. Withoutthe addition of the carbon black, it was impossible to dissolve thesoaps into the polymer.

The soaps that I have used are aluminum stearate of the mono, di, andtri types, mixtures of the mono, di and tri types, as well as mixturesof the tri and di, the di and mono, and di and tri types, all ofaluminum stearate. l have also used barium stearates, calcium stearates,magnesium stearates, lead oleates, naphthenate soaps of zinc, magnesium,lead, cobalt, and aluminum, oleate soaps of calcium, barium, aluminum,magnesium, and lithium, lithium stearate, strontium stearate. None ofthese soaps could be incorporated into the polymer in any noticeableproportion without the addition of the carbon black, but with theaddition of the carbon black to the polymer, all of these soaps could beincorporated and added some thickening action to the polymer. Thus theinvention contemplates the incorporation of substantially any metallicsoap into a synthetic liquid polysulfide polymer in the presence ofuniformly distributed carbon black which seems to make the solutionpossible. In addition I believe that the uniformly dispersed carbonblack in the mixture retains the solution of the polysulfide and soapduring its useful life.

In practicing the invention I have incorporated into the polymers, usingthe foregoing various types of metallic soaps, other carbon blacks todetermine their properties in this polymer. The carbon blacks that havebeen tried are easy-process channel, medium-process channel, hardprocesschannel, low-flow channel, medium-color channel, high-color channel,fine-furnace, high-modulus furnace, semi-reinforced furnace andpure-tone furnace. All of these grades and types of carbon blacks couldbe incorporated into the polymer, but none produced as good or aspronounced thickening action as the channel blacks made by burning gasor oil and particularly the mediumchannel air-floated carbon black.

In general I have found that substantially all of the foregoing carbonblacks could be incorporated to produce pronounced thickening of thepolymer and soap mixtures. However, it seemed that where the averageparticle size was larger than 5 microns the carbon black acted more orless as fillers and did not impart worthwhile thickening or gelling ofthe polymer and soap mixture.

For substantially any given particle size of carbon black the optimumthickening action of the metallic soap occurs when the pH range of thecarbon black is between 3.0 and 4.6. The carbon blacks which producedthe greatest and most desirable thickening action and the most stableand non-bleeding lubricants are those having an average particle size ofbetween 0.15 and 0.25 millimicron and having a medium acid pH of about 3to 4.6. I found that carbon blacks having an acid pH of about 3 to 4.6allowed the soap to be incorporated with the polymer very eificientlyand desirably even when the average particle size was as high as 0.02micron. The carbon blacks on the alkaline side with pH of about 7.9 to10, which are mostly furnace blacks, permit rather limited solubility ofthe soap into the polymer and were not as desirable, and I found that ingeneral the solubility of the soap in the polymer and consequently thethickening action decreased as the pH increases or decreases from themedium acid range of 3 to 4.6.

Actually the best results were obtained using an aluminum stearate withmedium-channel air-floated carbon black having an average particle sizeof about 0.21 millimicron and a pH of about 3.7. This was ratherunexpected since this type of carbon black is normally used as a paintor ink coloring and not for rubber reenforcing or the like. The soapwhich gave the widest temperature range in the lubricant and sealingmaterial and gave the best sealing and film strength was an aluminumstearate of a mixture of di and tri with a total ash content of 6.10 to6.25 percent.

It is my theory that the carbon black serves as a coupling agentpromoting incorporation of the polymer and metallic soap, although thisis the first time to my knowledge that carbon black has functioned as acoupling agent to any compounds.

For the preferred embodiment of the invention 1 prepare a satisfactoryoil field service plug valve lubricant and Percent Thiokol liquidpolymer LP-2 55-75 Thiokol liquid polymer LP-3 0-5 Carbon black, mediumchannel air-floated 14.5-6.0 Aluminum stearate, di and tri mixture(6.10-

6.25% ash) 30-10 Mica 0.5-4.0

As this is the minimum and maximum percentage range of this formula, mypreferred formula is as follows:

Percent Thiokol liquid polymer LP-2 67.5 Thiokol liquid polymer LP-3 2.5Carbon black, medium-channel air-floated 9.0 Aluminum stearate, di andtri mixture 20.0 Mica 1.0

In the above illustrative embodiments of the invention, Thiokol liquidpolymers LP-2 and LP-3 are identified as having substantially thefollowing average structure:

where X is an integer of about 6 for polymers of molec ular weight of1000 and X is an integer of about 23 for polymers of molecular weight of4000. LP-2 has an average molecular weight of 4000 and LP-3 has anaverage molecular weight of 1000. These are the same organic liquidsulphide polymers identified and described hereinbefore in column 2.

In the preparation of lubricant composition of the invention, I foundthat a definite procedure must be followed. For example, if the carbonblack is added to the liquid polymers first and the mixture heated above150 F. before the aluminum stearate is added, an incomplete gelling ofthe aluminum soap results. I have also found that if the aluminumstearate is incorporated into the liquid polymer before the carbonblack, there is a tendency for separation in the final product.

My preferred procedure for preparation is to first introduce the liquidpolymers into a heat jacketed kettle having a paddle or other agitator.The agitator is started and the heat turned on. The polymer mixture isheated to approximately F. The carbon black is then added into thekettle at a medium rate, while maintaining agitation and keeping thetemperature of the mixture between 125150 F. After all of the carbonblack has been added, the mixture is agitated for ten minutes. Then thealuminum stearate is added, all the while maintaining agitation andkeeping the temperature at approximately F. Care should be taken not tolet it exceed 150 F. by any substantial amount for any noticeableperiod. After all of the aluminum stearate has been added, the mica isadded. As soon as all of the mica has been added, increase the heat onthe kettle and heat the mixture to approximately 385 F., and maintainthis temperature with agitation for 20 minutes. The composition is thendischarged into cooling pans for rapid cooling and allowed to cool toroom temperature.

After cooling to room temperature, the composition is rolled by threepasses through a rubber mill roller or is shot through a homogenizer tobreak up the soap crystals. In practice and because of the odor of thiscomposition, during the process I incorporate a masking agent which maybe about 1%. to 1 /2 percent of the total formula.

A satisfactory masking agent is composed of approximately 80 percent ofNeutralizer 1A1, which is an odor depresslng oil manufactured by Magnus,Mabee & Reynard, Inc, and 20 percent Santomask, which is an odor maskingliquid manufactured by the Monsanto Chemical Company. The masking agenthas no effect on the properties of the composition and it is there onlyto cut down the mercaptan and dithiol odors of the composition, so thatany suitable masking agent inert with respect to the soap and polymersmay be used.

The lubricant composition which I have just described 18 a general oilfield lubricant and is resistant to those types of services, such asoils, gases, hydrocarbons, both liquids and gaseous, and mixtures ofoils and water, hydrogen sulfide, and mercaptans, both mixed with hydrocarbons and unmixed, and also has excellent resistance to drilling mudservices. This lubricant composition also is resistant to weak sulfuric,hydrochloric, and organic acids of about percent strength and Weakalkalies up to about a pH 13. It is completely unsuitable and is notrecommended for strong oxidizing materials such as nitric acids or likeoxidizing compounds. While it is not completely resistant to aromatichydrocarbons, such as benzene and toluene, in the field this lubricantcomposition acts very satisfactorily as a seal and lubricating ma terialin plug valves on aromatic services. One of the main properties of thislubricant and sealing composition of the invention, aside from itscomplete inertness to these aliphatic hydrocarbons, oils, and etc., isits preferential wetting action. Should the metal bearing or seatingcontact surfaces of the valve for example, become wetted with the linefluids, such as gasoline or oil, this lubricant composition willactually replace the line fluid on the metal and adhere tightly to themetal surfaces and exclude the line fluid from those surfaces.

It also exhibits a phenomena which gives it excellent load-carryingproperties for high pressure gas lines such as are encountered inChristmas tree services. On the steel and iron types of valves, thelubricant composition actually chemically reacts on the seating surfacesto form a corrosive product, which in turn appears to have an attractionfor the lubricant and resists being forced out by the line plug-loadingpressures. It also has been found that once this corrosive product(which is of microscopic magnitude in thickness) is produced on themetal seating surfaces of the valve, the lubricant is almost impossibleto remove during normal valve operation or by solvent action, even bythe solvents to which it is not completely resistant, that is, itperforms satisfactorily in service on lines carrying chlorinatedhydrocarbons and aromatic hydrocarbons.

Field tests have been made on this lubricant for a number of months, andindications appear that it is the only one general oil field servicelubricant with a wide temperature range of from 0 F. to plus 300 F. andresistant to the types of line fluid which are encountered in this typeof service available today.

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The presentembodiment is therefore to be considered in all respects as illustrativeand not restrictive, the scope of the invention being indicated by theappended claims rather than by the foregoing description, and allchanges which come within the meaning and range of equivalency of theclaims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States LettersPatent is:

1. A lubricating and sealing composition suitable for use in plug valvescomprising substantially from 55 to 75 parts of a synthetic liquidorganic polysulfide polymer having an average molecular weight of about4000; from 0 to 5 parts of a synthetic liquid organic polysulfidepolymer having an average molecular weight of about 1000; saidpolysulfide polymers having substantially the following averagestructure:

where X is an integer of about 6 for polymers of molecular weight of1000 and X is an integer of about 23 for polymers of molecular weight of4000; from 10 to 30 parts of at least one metallic non-water solublesoap selected from the group consisting of the soaps from stearic, oleicand naphthenic acids; and from 6 to 14.5 parts of medium-channelair-floated carbon black having an average particle size of less than 5microns and a pH value of about 3 to 4.6.

2. The composition of claim 1 in which the metallic soap is aluminumstearate.

3. The composition of claim 1 in which there is present about 0.5 to 4parts mica particles.

4. The process of making a flowable plastic mass suitable for use as aplug valve lubricant and sealant comprising heating to about 125 F.,from 55 to parts of a synthetic liquid organic polysulfide polymerhaving an average molecular weight of about 4000; and from 0 to 5 partsof a synthetic liquid organic polysulfide polymer having an averagemolecular weight of about 1000; said polysulfide polymers havingsubstantially the following average structure:

where X is an integer of about 6 for polymers of molecular weight of1000 and X is an interger of about 23 for polymers of molecular weightof 4000; then adding from 6 to 14.5 parts of carbon black having a pH offrom 3.0 to 4.6 while keeping the temperature of the mixture between F.and F.; then adding from 10 to 30 parts of a metallic non-water solublesoap selected from the group consisting of the soaps from stearic, oleicand naphthenic acids, while maintaining the temperature of the mixturefrom substantially exceeding 150 F. to thicken the mixture to desiredconsistency; agitating and raising the temperature of the mixture toabout 385 F., and then cooling the mixture to about room temperature.

5. In the process defined in claim 4, the further step of working thecooled mixture mechanically.

References Cited in the file of this patent UNITED STATES PATENTS2,467,146 Morway et al. Apr. 12, 1949 2,467,148 Morway et a1. Apr. 12,1949 2,474,859 Perkins July 5, 1949 2,477,311 Morway July 26, 19492,484,369 Ballard et a1. Oct. 11, 1949 2,487,260 Morway Nov. 8, 19492,522,460 Morway et al. Sept. 12, 1950 2,562,144 Harman et al. July 24,1951 2,653,131 OHalloran Sept. 22, 1953 2,668,757 Hansley Feb. 9, 19542,696,469 OHalloran Dec. 7, 1954 OTHER REFERENCES Polysulfide Polymers,by Fettes et al., Ind. & Eng. Chem, vol. 42, pages 2217 to 2223,November 1950.

Polysulfide Liquid Polymers, by Jorczak et al., Ind. & Eng. Chem, vol.43, pages 324 to 328, February 1951.

Thiokol, Liquid Polymer L. P. 2, published by Thiokol Corporation,Trenton, N. I.

1. A LUBRICATING AND SEALING COMPOSTION SUITABLE FOR USE IN PLUG VALVESCOMPRISING SUBSTATIALLY FROM 55 TO 75 PARTS OF A SYNTHETIC LIQUIDORGANIC POLYSULFIDE POLYMER HAVING AN AVERAGE MOLECULAR WEIGHT OF ABOUT4000; FROM 0 TO 5 PARTS OF A SYNTHETIC LIQUID ORGANIC POLYSULFIDEPOLYMER HAVING AN AVERAGE MOLECULAR WEIGHT OF ABOUT 1000; SAIDPOLYSULFIDE POLYMERS HAVING SUBSTANTIALLY THE FOLLOWING AVERAGESTRUCTURE: